1. Field of the Invention
The present invention relates to a donor substrate for Laser Induced Thermal Imaging (LITI) method, and more particularly, to a donor substrate for Laser Induced Thermal Imaging (LITI) method comprising a mixture of laser induced thermal imaging enabling phosphorescent materials as a light-emitting substance.
2. Description of the Related Art
Generally, an organic electroluminescent device includes an anode and a cathode, a hole injection layer, a hole transport layer, an emission layer, an electron transport layer and an electron injection layer. The organic electroluminescent (hereinafter referred to as EL) device is classified into a fluorescent device which uses a singlet and a phosphorescent device which uses a triplet, according to a light-emitting mechanism, and a high molecular weight device and a low molecular weight device according to materials used. In case of the low molecular weight organic EL device, each of the layers is introduced by a vacuum-deposition. In case of the high molecular weight organic EL device, a light-emitting device is fabricated using, for example, a spin-coating process or an inkjet process.
Recently, an organic EL device is spotlighted as a large area providing material since it has a high efficiency compared with a fluorescent material.
A low molecular weight organic EL device is disadvantageous in terms of a mass-production since a full color device is fabricated by depositing each layer using a mask while a fluorescent device and a phosphorescent device are fabricated by introducing each layer using a vacuum-deposition. Patents and Publications on a low molecular weight organic EL device include U.S. Pat. Nos. 6,310,360, 6,303,238, 6,097,147, and International Patent Publication Nos. WO 00/70655, WO 01/39234, WO 01/93642 and WO 02/15645.
These patents and publications do not relate to a patterning process using a laser induced thermal imaging or an ink jet printing, but rather to a composition and a material of a phosphorescent device by way of a deposition. In case of a high molecular weight device, although many devices using a fluorescent material have been studied, research materials on devices using a phosphorescent material are disclosed in Japanese Patent Application No. 2000-68363.
An organic polymer EL device has merits in that it is advantageous to fabricate a large area device since a light-emitting device can be fabricated using a spin-coating process. However, devices using a phosphorescent material have not been reported regardless of their possibility since they are limited in the spin-coating process.